Field
The present invention provides fast fixturing two part adhesive compositions which include a first part containing a (meth)acrylic component and a cure system for the epoxy resin component of the second part and a second part containing an epoxy resin component and a cure system for the (meth)acrylic component of the first part.
Brief Description of Related Technology
One approach to these adhesives are (meth)acrylates with reactive crosslinkers, such as epoxides. Acrylic-based adhesive compositions are well known. See e.g. U.S. Pat. No. 4,536,546 (Briggs). While adhesives based on this technology appear to have been sold under the tradename PLEXUS MA 300 and 310 by Illinois Tool Works Inc., Chicago, Ill., they can exhibit an obnoxious odor and they are toxic to handle, which are significant drawbacks to their use.
Two-part epoxy resin compositions are also known, where one of the parts includes an acrylic-based adhesive. For instance, U.S. Pat. No. 4,426,243 (Briggs) describes an adhesive composition that is prepared from two different adhesive materials, one being an epoxy resin and the other an acrylate-based adhesive, being chemically bonded together by a bifunctional component having as one of its functional groups an epoxy and as the other an acrylate. See also U.K. Patent No. GB 2166447B.
U.S. Patent Application Publication No. US2010/0065210 provides a sag-resistant composition including: (a) a first part which includes: (i) a (meth)acrylic component, (ii) an amine catalyst; (iii) an optional second catalyst; (iv) a reactive acid component, and (v) a free-radical inhibitor; and (b) a second part which includes: (i) a resin component which includes epoxy groups, (ii) a peroxide; and (iii) a metal compound which complexes with the strong acid component and which is substantially non-reactive with the peroxide. The first and second parts are of sufficiently low viscosity to be easily dispensed with a pumping apparatus. To form this adhesive, the first and second parts are mixed, and immediately after mixing, the mixture is of a higher viscosity, such that the adhesive does not sag, drip, or migrate, after application to a surface within the open time of the mixture, and the mixed first and second parts cure. By the term “open time” is meant the elapsed time between the mixture of the adhesive to the curing.
Existing compositions do not possess the desired fast fixturing and good adhesion properties for the assembly of laminates, such as hand held display devices.